OpenVPN client not using specified interface
I'm not sure when this problem started. It may have been today with the 2.2.1 update, or it could have been 2.2…I'm trying to dig up old logs and find out.
Anyways...I have an OpenVPN client set up to connect to a server at another site (TUN, UDP, Remote Access SSL/TLS, TLS auth key). In the client config, I have a specific interface selected (it's ppp/4G for emergency access and it is up/configured/working) that I want to client to use for going outbound. However, the client is connecting out the main WAN interface. Tcpdump on the ppp interface shows no traffic when the client connects. OpenVPN status on the remote site shows a successful connection from my WAN interface. I've removed and re-configured the 4g interface, the client and the server and that didn't help.
So, did some more digging. It first started on December 3, 2014. Looks like late on December 2, I changed from automatic outbound nat to manual and created a few mappings. Can that be causing the problem somehow? Strangely, even since then, it seems like sometimes it will use the 4g/ppp interface.
Outbound NAT settings should have no effect on where the OPenVPN client originates from.
From your description the OepnVPN client should be locked to the specific interface you have selected for it.
I do not know what to suggest other than post some screen shots of OpenVPN client settings and your Interfaces and maybe someone can spot a setup issue.
And look for other changes in early December.
It seems the NAT settings were the culprit. I changed to the new outbound nat hybrid mode, and removed a "catch all" rule I had entered (which I think was a bad idea), and things are working good now.